The present invention relates to automatic defrost controls for two compartment refrigerators, and more particularly to automatic defrost controllers including air damper control.
Refrigerators having two refrigeration compartments, including a fresh food compartment and a frozen food compartment, are well known. Many of these two compartment refrigerators have refrigeration apparatus connected to the frozen food compartment and a duct for carrying cool air from the frozen food compartment to the fresh food compartment. In order to regulate the temperature of the fresh food compartment, a damper or baffle is often provided within or adjacent to the duct. The baffle is thermostatically controlled to provide a desired temperature within the fresh food compartment.
Self defrosting refrigerators generally include a defrost heater for melting ice that has accumulated on the refrigeration apparatus. However, the operation of the defrost heater will often cause water to accumulate on or near the air duct damper. Subsequently, especially when the cooling apparatus is operated, the water can freeze and form ice that interferes with the effective operation of the damper.
In order to avoid this problem, a number of solution has been proposed. In U.S. Pat. No. 5,201,888 to Beach et al. a control moves the damper to a fully closed position while energizing the defrost heater. Thus, the formation of condensation and subsequent ice formation is reduced. However, water can still accumulate on the baffle, which later freezes, especially when the defrost heater must be operated for an extended period of time.
U.S. Pat. No. 5,375,413 to Fredell et al. discloses a two-element sliding air baffle for a refrigerator. The second baffle element is operated by a solenoid that, in a closed position, is periodically pulsed (every one minute) thereby exerting a repeated rocking or leveraging motion on the second baffle member. The rocking motion enhances the break up of any ice that has formed between the two baffle elements. However, once ice has formed, it can be very difficult to remove.
Further, energy conservation is becoming more and more important in appliances such as refrigerators. Although many energy saving measures have been developed, there are significant inefficiencies in the operation of such refrigerators.
Thus, there is a need for a refrigerator capable of preventing the build-up of ice on an air duct damper. Further, there is a need for improving the energy efficiency of refrigerators.